Cysts of the colonial dinoflagellate polykrikos schwartzii Bütschli 1873, (gymnodiniales), from recent sediments, firth of forth, Scotland

Abstract

Cysts of the colonial gymnodinialean dinoflagellate Polykrikos schwartzii Bütschli 1873, recovered from Recent sediments in the Firth of Forth, Scotland, are shown to be extremely variable in morphology, especially in regard to their wall structure and reticulate ornamentation. The cysts are, however, based upon a relatively simple plan with each elongate cyst carrying seven whorls of ornament. No clear or simple dinoflagellate paratabulation is discernible but an apical archeopyle is described together with possible details around the archeopyle margin. These cysts may provide information about the nature of “primitive”; tabulations because of their similarity with some fossil dinoflagellate cysts. The distribution of Polykrikos cysts in Recent sediments is described from both the Firth of Forth, the North Atlantic, and around the British Isles. The known autecology suggests the possible usefulness of P. schwartzii cysts in the interpretation of environments, particularly climate, within the Quaternary record.